The present invention relates to a resist-treating apparatus, i.e., apparatus for coating a substrate such as an LCD substrate or a semiconductor wafer, with resist, followed by developing the resist coating, and to a resist-treating method.
In the manufacture of a liquid crystal display (LCD) device, a photolithography technology similar to that employed in the manufacture of a semiconductor device is utilized in general for forming an ITO (indium tin oxide) thin film or an electrode pattern on a glass substrate of the LCD device. In the photolithography technology, a substrate is coated with a photoresist, followed by selectively exposing the coating to light and subsequently developing the exposed pattern.
In the resist coating step, a rotary cup type resist coating apparatus, in which a cup is rotated together with a substrate, is used in order to coat the substrate surface with a resist uniformly. FIG. 1 shows the rotary cup type coating apparatus disclosed in U.S. patent application Ser. No. 08/416,368 filed by the present applicants on Apr. 4, 1995. As shown in the drawing, a spin chuck 10 and a cup 20 are commonly connected to the driving shaft of a motor 1 via timing belts 2, with the result that these spin chuck 10 and cup 20 are rotated in synchronism.
In the conventional apparatus shown in FIG. 1, an upper lid 30 is lifted upward by a robot arm 40, followed by transferring a substrate G onto the spin chuck 10 by operating a main arm (not shown) of a substrate transfer mechanism. The substrate G is held on the spin chuck 10 by vacuum suction. Under this condition, a nozzle (not shown) is positioned upward of the substrate G so as to allow a resist solution to be dripped from the nozzle onto the upper surface of the substrate G. When the nozzle is retreated, the robot arm 40 is operated again to put the upper lid 30 to close the upper opening of the cup 20 so as to form a hermetic treating space 21. Under this condition, the spin chuck 10, cup 20, lid 30 and substrate G are rotated in synchronism, with the result that a resist coating film is centrifugally formed in a uniform thickness on the upper surface of the substrate G.
With increases in the degree of integration and fineness of the semiconductor devices and with enlargement of the semiconductor wafers, the cup 20 tends to be enlarged in recent years. What should be noted is that the cup 20, which is enlarged, and the spin chuck 10 have a large inertia moment, making it difficult to accelerate or decelerate these cup 20 and spin chuck 10 promptly. In other words, it takes an unduly long time for these cup 20 and spin chuck 10 to reach a predetermined rotation speed (rpm) from the start-up time. Likewise, an unduly long time is required for the cup 20 and spin chuck 10, which are rotated at a predetermined operating speed, to be stopped completely. It follows that the through-put of the apparatus is lowered.
It may be reasonable to use a large motor for overcoming the above-noted problem. If both the spin chuck 10 and cup 20 are rotated by a large motor, however, a power consumption is increased. Further, in the case of using a large motor, the coating apparatus is rendered bulky. Naturally, the treating system and the auxiliary facilities thereof are rendered bulky as a whole.